Wraiths are a weird phenomenon, rare enough that the majority of the The Mythos refers to six of the Seven Peoples of the Earth, i.e. the Sun and the Darkness, the Guardians and the Dream, and the Fey and the Kin. "Among the Mythos, who are you?" is the standard greeting, regardless of language. It's a polite way of inquiring the other's heritage, which then gives the one who asked some idea... has no idea they exist.
For the record, they are not Ghosts are one of the few remaining members of the Dream to be part of our world. They are not, sadly, actually dead people; when people are dead, their souls go elsewhere. Ghosts are echoes; as dreams often bring to mind things once forgotten (and similarly, we think we forget the things we dream), so sometimes members of the Dream.... Ghosts are echoes of people who’ve died. Wraiths, on the other hand, are pieces of beings who have died and who can never be whole, for most of their essential selves has been destroyed.
Hades is one of the ancient, strange beings known as gods. His father, Cronus ate him, for reasons unknown; his sister Dis defeated Cronus and freed him, but he wasn't right when he came out. Like the People of the Sun, these so-called gods are not separate from their bodies; they are one thing, spirit and flesh, and so when the... – Death – cares for these beings, though the details are unclear. He’s lent a few to Name meaning: Night (Italian - he picked that one) Other names: Naktam (sanskrit); Night-child; Nox Eterna; the Blood King. He's probably the oldest living creature among the Mythos. The father of all vampires (or Night Children, as they're called), he's a mystery; no one knows where the heck he came from, or who made him. It says a lot that... as servants, which can be deeply startling for visitors.
A white thing—a puff, a phantom, a see-through blobby shape like a pillowcase underwater—flew through the wall and between them, bringing with it a cold wind and wearing an impossibly solid red bowtie near its top. […] It had a shape, of sorts—curvy and blobby and really not humanoid. There were no limbs. The red bow-tie indicated the possibility of a head, but there was no face; above the tie, the blob tapered, ending in a sort of empty-windsock sag.